In the the picture when you see the bottom of the connecting rod the bolt looks like it came loose. I wasnt in the connecting rod when I pulled the pieces outta the pump.
I can see in your first photos some damage to the top of the casing that looks like a broken piece got caught between the next piston and the top of the case.
I've seen a General pump where somehow both the bolts backed completely out and the connecting rod end just fell off with no damage. It was one of the hardest problems to diagnose I've seen because the pump was perfectly smooth on rinse (The water pressure kept the piston pushed tight against the crankshaft) but it was rough and weak on gravity-feed. I bolted the parts back together and the pump ran fine for years after.