Bad Hadraulic Lifters, Maybe?

Looking at that pump,, I'd say it never turned, or stopped turning, and the shaft kept turning ,,

I'd want to find out what stopped the gears in the pump..

Everything but pump and the shaft will likely be okay.. my .02

Tap the shaft out from the bottom.. use a 3/8 extension, or your primer, gently, perhaps.

And before installing the new pump,, try turning it by hand.. .