Non veni pacem mittere, sed gladium.
Suggestion: Get a conventional portable generator of about 11HP or 5500W. It will run your 240v well pump, and it will run your water heater. The smaller "suitcase" inverter units are wonderful for camping and running a fridge or a window AC unit. But they do not put out 240V, and don't have the starting umph to run bigger motors. The inverter units are fuel efficient at low loads, and will save fuel. Or, simply turn off your larger unit when not being used.
He's right, those smaller gensets, while nice, won't do your well. They will start on skillsaw, but not two, for example. And that is at 110VAC. Yer well is likely 220V.
EMP will fry your generator, and anything electronic you want to plug in, that isn't in a faraday cage.