Can I replace a MBP 2012 SSD with the Flash storage from a MBP 2013? My son's MBP (13-inch, Mid 2012) internal SSD has been acting strangely enough that I'm starting to wonder if it needs to be replaced (do SSDs fail?). I have a MBP (retina 15-inch, Early 2013) with a failing logic/graphics board combo that I'm going to need to replace anyway.

Can I take the 512 GB flash storage from my 2013 MBP and put it into my son's machine? I realize that the process may be arduous, I just wanted to find out if it's even compatible.

Thanks!
Out of the box, definable you not.  The 2013 MacBook Pro laptops use a proprietary PCIe interface whereas the 2012 used a SATA III interface.  

There may be a PCIe to SATA adapter, but I haven seen any that are compatible with the Mac’s proprietary interface.  Even so, SATA SSDs are very cost effective right now, so it’s not practical to add that extra layer of complexity by putting an adapter into the mix.