I do not have firsthand experience with issues of this nature except on metal equipment used in saltwater.
Current is not measured in volts, but in amps.
A measured voltage of 10 volts indicates that there is active corrosive force, in essence your well is a functioning battery.
The well water is acting as an electrolyte, and your pump is the anode. The solution in saltwater is to attach a large piece of zinc to the metal which is dissolving rapidly as a sacrificial anode. This is due to zinc having a greater affinity for being dissolved.
Is this well strictly for agriculture? I don't know if zinc toxicity is an issue that has to be considered in this situation, but it would be the solution for a pump operating in saltwater.
What type of damage is causing the failure? There may be an opportunity to change the pump design to eliminate the problem.
They have zinc or magnesium electrodes in the ground but instead of oxidating those electrodes,it oxidates my well pumps,cables ,door valves ,etc.
I was thinking to install a pump that doesnt gets in contact with the water ,but the well its verry deep( 37 meters deep on one meter wide concrete tubes) and its hard to find such pump.
Right now i have installed a russian pump made 35 years ago wich worked flawlessly for 35 years in another well.The guy i bought the pump sold it because the cable started to crack a little but i reconditioned it.Its a membrane,high pressure pump that doesnt have bearings or a motor,just a vibrating coil( electromagnet) that actions the membrane.Its a verry efficient pump that draws only 200 watts to get a decent flow of water from that depth.In comparison i had german ,chinese and romanian pumps that had brushless motor with bearings that consumed at least 1000 watts for the same flow the 200 watts russian pump gives..They all rusted altough were from stainless steel or bronze and the pumps with motor lost the oil in the well ( the motor of such pumps its filled with oil wich its pretty weird for an electric motor).
The well i use it for my orchard and i plan to use it for my greenhouse and a small scale trout farm.