Since this occurred immediately following an impeller change, one possibility is that the pump cover plate and
gasket or o-ring may not have been properly re-installed when the impeller was replaced. An air leak at the cover plate can prevent the pump from priming fully, the impeller will run dry or partially dry and will quickly be destroyed.
Another possibility is that flow to the pump was disrupted by a blockage in the system between the through-hull and the pump. To check this, first verify that water can actually get to the pump. Check that the through-hull is clear (and open), any fittings downstream of the through-hull are clear, hoses are clear, and the strainer is clear. Make sure all connections upstream of the pump (suction side) are air-tight (hoses and strainer cover). Next, make sure that the pump cover plate is sealed tightly against its
gasket or o-ring (replace these while you're at it). If located above the water line, the pump should self-prime.
A final possibility is that the system downstream of the pump is blocked, preventing air from leaving the pump. Check that hoses, heat exchanger and mixing
elbow are clear and that the anti-siphon device, if there is one, is working.
Start the engine and keep an eye on the exhaust for adequate water flow and the temperature gauge, if there is one, for engine temp.