General pump keeps breaking valve seats

Any experience with this? 15 years in business, never seen a pump do this. I'd estimate a valve seat (any of them) cracks and breaks every 40 to 80 hours. I normally run TS2021s but is a TS1321. It is rated at less psi and GPM than the TS2021 but yet it has a larger bore, 22mm vs 20mm. Thanks for you time and experience!

look for flow restriction in the feed line..
..did you change plumbing ??
Has it been pulsating ??
Did you change the unloader ??
How high is "spike-pressure" over the working pressure??
Was the pump new or used ??

Call me if you want this to go fast.

The pump was used in a way. We have three rigs, but they are separately maintained. I don't know much about it. When I installed it, I installed new plumbing, mostly 3/4" for a couple feet, then into 1/2" pipe as I always do. It doesn't pulsate until a valve seat cracks. Same unloader as was used with the 2021, I don't run it full pressure so it doesn't spike much. Sorry, not a lot of clues. Its suppose to run at 1150 rpm, 2100 psi, 5.5 gpm. I'd bet I'm running closer to 6.5 gpm, 2500 psi, and 1450 rpm. That could be the problem, but I've overrun my TS2021s for years, they are bulletproof outside of needing packings or scored plunger from time to time.