So I was going to make a DIY for the front speakers too, but there's no point, because this one is more comprehensive than anything I would make.
2013 Ford Escape Factory Speaker Replacement
With that said, there aren't any DIYs out there for rear speakers, and they have some interesting quirks that I discovered while installing my new Alpines. So here we go.
Tools needed:

7mm socket
7/32 socket (if you need to replace the stock plastic speaker mounts. I didn't)
Ratchet
Socket extension (you don't need a 10" one like mine)
Flathead screwdriver
Something skinny to pry apart/off body panels
Phillips head screwdriver
Electric drill
Electrical tape and scissors or whatever you use to splice your wires
Step 1:
Locate screw at the bottom of the door panel and remove it with the 7mm socket

Step 2:
Use your skinny tool and pry off the top of the door pull. I pried mine up with a skinny punch and then slipped the flathead screwdriver. It's only attached with clips, but be gentle and pop them out carefully.

Step 3:
Remove the window controls by disconnecting the harness. Then use the 7mm socket to remove the screw inside the panel.

Step 4:
Locate the screw further down the door pull and use the 7mm socket to remove. Because careful, because it is deep in there and can drop down into the body panel.

Step 5:
Pull back the door handle and slip your skinny tool in the crack behind it. That small panel pops out and one more screw is hiding back there for your 7mm socket.

Step 6:
Go back to the bottom of the door panel and slip your flathead carefully underneath it. Pry back gently until the first of the clips holding the panel to the frame pops out. You can then get your fingers underneath and pop off the rest of the clips around the edges of the panel.

When you've done this, lift the panel straight up and unclip the harness for the factory tweeter. DO NOT REMOVE THE DOOR HANDLE LINE.
Step 7:
Here's your stock speaker in all its awful glory. Remove the white harness. You'll notice there are four wires. That's because the rear tweeter is also powered by the rear speaker. Surprise! The second and third wires are for the tweeter and the first and fourth are for the speaker. Pull this out. They just slip from connector with a little force.

Here are the two wires you will use.
Step 8:
Install your new, spiffy speakers. I didn't include any pictures of me doing this because every install will vary, and if you don't know how to do basic wiring, you probably shouldn't be doing this. The Alpines I installed used their adapter to mount directly to the factory adapter. There was a small gap, so I was able to run my wiring through this and behind the speaker adapter, as seen below. If you don't want to do this, there is a small black rubber gasket that you can slit a hole in and push your wires through.

You'll also notice that I did not reuse the factory tweeters. The ones installed on the Alpines were fine with me, and I like my music a certain way, so I don't miss the factory tweeters. I also merely stripped the ends of my new wires and threaded them through the factory metal connectors before securing with electrical tape. If you wish to do a more factory install, you can remove the metal connectors and solder, heat shrink, etc. I didn't do this, because when I sell this car, I'll pull these speakers out, and I wanted to leave all the factory wiring as is. DON'T FORGET TO TEST YOUR SPEAKERS BEFORE PUTTING THE PANEL BACK ON.
Step 9:
Reinstall door panels in reverse order from above.
IMPORTANT: Thread the window control harness through its opening before reattaching all the door panel clips, or else you'll have to remove the panel again, because that thing gets pinned back there tightly. Also, you might want to keep a magnetic headed bit around so that you don't drop the 7mm screw behind the door panel where you need to use your extension. I did this twice, and it's a PITA. Don't forget to reattach all wiring harnesses.
Anyway, that's it. It's pretty simple, but I always found it easier if I had some idea of what I was doing. The driver's side panel took me about 15 minutes, since I was learning as I went. The passenger side took me about 10 minutes.
2013 Ford Escape Factory Speaker Replacement
With that said, there aren't any DIYs out there for rear speakers, and they have some interesting quirks that I discovered while installing my new Alpines. So here we go.
Tools needed:

7mm socket
7/32 socket (if you need to replace the stock plastic speaker mounts. I didn't)
Ratchet
Socket extension (you don't need a 10" one like mine)
Flathead screwdriver
Something skinny to pry apart/off body panels
Phillips head screwdriver
Electric drill
Electrical tape and scissors or whatever you use to splice your wires
Step 1:
Locate screw at the bottom of the door panel and remove it with the 7mm socket

Step 2:
Use your skinny tool and pry off the top of the door pull. I pried mine up with a skinny punch and then slipped the flathead screwdriver. It's only attached with clips, but be gentle and pop them out carefully.

Step 3:
Remove the window controls by disconnecting the harness. Then use the 7mm socket to remove the screw inside the panel.

Step 4:
Locate the screw further down the door pull and use the 7mm socket to remove. Because careful, because it is deep in there and can drop down into the body panel.

Step 5:
Pull back the door handle and slip your skinny tool in the crack behind it. That small panel pops out and one more screw is hiding back there for your 7mm socket.

Step 6:
Go back to the bottom of the door panel and slip your flathead carefully underneath it. Pry back gently until the first of the clips holding the panel to the frame pops out. You can then get your fingers underneath and pop off the rest of the clips around the edges of the panel.

When you've done this, lift the panel straight up and unclip the harness for the factory tweeter. DO NOT REMOVE THE DOOR HANDLE LINE.
Step 7:
Here's your stock speaker in all its awful glory. Remove the white harness. You'll notice there are four wires. That's because the rear tweeter is also powered by the rear speaker. Surprise! The second and third wires are for the tweeter and the first and fourth are for the speaker. Pull this out. They just slip from connector with a little force.

Here are the two wires you will use.

Step 8:
Install your new, spiffy speakers. I didn't include any pictures of me doing this because every install will vary, and if you don't know how to do basic wiring, you probably shouldn't be doing this. The Alpines I installed used their adapter to mount directly to the factory adapter. There was a small gap, so I was able to run my wiring through this and behind the speaker adapter, as seen below. If you don't want to do this, there is a small black rubber gasket that you can slit a hole in and push your wires through.

You'll also notice that I did not reuse the factory tweeters. The ones installed on the Alpines were fine with me, and I like my music a certain way, so I don't miss the factory tweeters. I also merely stripped the ends of my new wires and threaded them through the factory metal connectors before securing with electrical tape. If you wish to do a more factory install, you can remove the metal connectors and solder, heat shrink, etc. I didn't do this, because when I sell this car, I'll pull these speakers out, and I wanted to leave all the factory wiring as is. DON'T FORGET TO TEST YOUR SPEAKERS BEFORE PUTTING THE PANEL BACK ON.
Step 9:
Reinstall door panels in reverse order from above.
IMPORTANT: Thread the window control harness through its opening before reattaching all the door panel clips, or else you'll have to remove the panel again, because that thing gets pinned back there tightly. Also, you might want to keep a magnetic headed bit around so that you don't drop the 7mm screw behind the door panel where you need to use your extension. I did this twice, and it's a PITA. Don't forget to reattach all wiring harnesses.
Anyway, that's it. It's pretty simple, but I always found it easier if I had some idea of what I was doing. The driver's side panel took me about 15 minutes, since I was learning as I went. The passenger side took me about 10 minutes.