Well Pump - self-test at least weekly, send a sample to the local test lab at least twice a year. Learn how to treat the well water.

Tank - As big as you can afford sized to how long you want torun your well pump; set up to gravity feed as and when necessary.

Water supply pump - figure out your domestic and other needs for pressurized water, then at least double the capacity of the pump.

Pond - Consider creating a retaining pond for a large reserve of water already pumped. Even a small pond with its own distribution filter/pump to distribute low pressure water to conserve and extend your high pressure system. Catches rain water as a secondary water source. Add some cattails and fish as survival food sources. Set up so when your tank is full the sytem pumps to the pond, and a float switch to turn off the pump when the pond is full. You will need to consider testing, filtering, and treating the water for domestic use.

Consider a separate grey water system to conserve your expensive potable well water.

Edit: look into roof catchment systems to capture rainwater.