Water Pressure Pump Switch contact damage

[radioFlash]

I'm going to go ahead and rewire the well shed with a proper sub-panel and grounding and reconfigure the pump to 240V. I'll look into installing RC snubbers and contactors. Thanks all for the suggestions.

[radioFlash]

I replaced the old wiring with a subpanel and the pressure pump was rewired for 240V. It now draws 10 A in operation and there is much less arcing when it switches on.

[floobydust]

Ahhh much better 
You might consider stuffing a MOV or snubber across the motor(s) terminals in one of the metal boxes, if the arcing is too much or radio interference etc. in a problem. Something that starts to clamp above say 275VRMS/350VDC like MOV-20D431K is small at 20mm.