It's a question whether you can provide power to the existing pump. You must not try to dismantle any part of the mechanical system. Suppose it were to stop working? Even if you did not break it, it will look as though you did.
It will be best if you can provide a different power source. It would be great if you can obtain a 3-phase generator, and hook it up to a truck engine which has a power take-off (a splined shaft extending out from the end of the crankshaft).
Only a knowledgeable electrician should rewire the 3-phase connections. Under no circumstances should an electrical generator be connected so that it could send power out onto the grid.
Other power sources might include solar panels, or wind turbines, etc. These are costly, and likely to produce basic DC, or 1-phase AC.
If you use DC, or 1-phase AC, then you will need a pump that works on that type of power.
As a last resort, you can have beasts (or people) turn a mechanical pump.
If you construct a different system, try to get it working by itself. If you connect anything to the existing pump system, make sure it can be restored to its original working condition, if you need to do so.
Someday we in America may be in the same situation you are in. And our population will likely not handle it peaceably, because we are so accustomed to life with reliable electricity.