Battery Backup for 240V (USA) Water Well
If you have not yet bought the pump, you may want to reconsider. If you buy a 3 phase pump, you can use a VFD to power it. Use a VFD that will accept a DC input directly, then you don't need the inverter (it IS an inverter). That will avoid the starting current surge of the motor, because  VFD controls that. The down sides: Your DC voltage for a 230V pump will need to be around 330VDC, so that's 28 12 volt batteries in series (I'd go 30 to give you some head room as the batteries get old). It's also going to be expensive.
Alternative #2; get a solar powered well pump, basically a Permanent Magnet DC pump motor, no inverter needed at all. Also expensive, but MUCH simpler.