Bad Pump ???

[DIXIEDOG]

I recently posted about a loader that wouldn't lift, it turned out to be a bad pump. When the hydraulic shop pulled it apart there were deep gouges in the aluminum housing. What would cause them? I didn't find any metal in my hydraulic oil when I drained it. Could it have been from ice in the winter because of having some water in my oil?

I'm just trying to get ideas before I put my new pump in and repeat the failure