It looks completely rebuildable to me.
That said, I took the stems from my shower to my local Ace hardware, and they matched them. The screw had snapped off, so I wasn’t sure I could back it out. And, I wanted to get the water back on.
While I was there I picked up all the parts to rebuild the ones I had. They are now rebuilt and waiting for another problems to crop up.
I’d suggest you get a seat wrench, and pull the seats so you can match and replace them at the same time.