Dealer is gonna say, "fuel contamination......no warranty"
The pumps have issues. Plastic parts in them and ANY water intrusion ALMOST always destroys them. The factory water separator is a joke at best and completely ineffective at worst. I suggest adding a water separator. $10k repair bill if they gong the warranty.
I think the plungers are tungsten and the barrells are stainless steel. At least thats what it looked like the last time I had a cp4 apart.
The body is aluminum.