always always use p.l.e.n.t.y. of electrical tape and tape wiring to well pipe ! Doesn't matter if it's steel or plastic, securely fasten the pump lead wires to the pipe.

Worked with a well pump guy more years ago than I care to remember,, he was fanatical about anything to do with the pump wire. We would go thru 4-5 rolls of electrical tape when installing a pump. He explained about 'rubbing',, and how more than once during a screwup,, the pump/pipe would get 'dropped' and the only thing that made that situation better was the pump/pipe was hauled up out of the hole strickly by the securely fastened well pump wire.