use of material

Ive had an electrolysis problem between my metal well pipe and my stainless pump, eats a hole, the well repair person cut the pipe, rethreaded it and reattached the pump. He wrapped the joint with electrical tape. 1 year later I begin to get a water-hammer although no water is running, and a small amount or air is present when the valve is open. Is the beginning of another electrolysis created pipe hole? Should I change the well pipe to Sch 80 PVC? any ideas would be helpful!