If your oil pump is actually bad then it will not be pumping oil or the oil pressure may be too low.
Driving with a bad oil pump is not recommended because the oil pump is the heart of your engine and without the oil pump working properly your engine will not get enough oil or any oil at all.
When your oil pump fails completely the engine will seize up and then you'll need a new engine or a rebuild of the engine.
A new oil pump is cheaper than a new engine or rebuilding the engine.
But you need to remove the oil pan on most engines to get to the oil pump.
The location of the oil pump varies on the vehicle you're driving.
It can cost you around $200.00 to $500.00 to have a new oil pump installed by a shop depending on the vehicle but if you can do it yourself then it may only cost you $50.00 to $150.00 depending on the cost of the oil pump.
You'll also need an oil pan gasket as well.