You will need to pull a new cable - the 120V circuit has one conductor less than needed for a 240V service (230V and 240V are often used interchangeably as are 115V and 120V but the nominal voltage reading between two live wires is 240V). Unless someone had a foresight of using a 240V pump in the future, your current cable has 3 wires and you need 4.
You will also need to install a new breaker - one that's able to disconnect both live wires when either one of them is tripped.Â
Is using a (smaller) 120V pump out of the question due to the flow requirement? It may be easier to find a different pump than to rewire. Depends on your situation of course, but keep the option of using a smaller pump open until you know all the costs involved. I would not be surprised if your rewiring bids came in at several times the cost of a new pump (additionally, you may be able to return the 240V one)