The engine oil pump is used to generate oil pressure needed to keep internal engine components lubricated. An oil pump change is needed if the oil pump fails and cannot lubricate internal engine parts, then major engine damage can occur.
How an oil pump change is performed depends upon where the oil pump is located and what drives the oil pump. If it is located in the engine oil pan, then the pan must be removed in order to replace the oil pump. If a timing belt operates the oil pump, then the engine's fan belts and timing components must be removed to gain access to the oil pump. If it is driven by the crankshaft, the accessory belts, timing cover, and crankshaft pulley have to be removed.
When performing an oil pump change it is important to follow manufacturer specifications found in your owner's manual.
Most manufacturers cover an oil pump change under the powertrain portion of the warranty if it fails due to manufacturer defect or workmanship. Extended car warrantys are also available that will not only extend coverage of the oil pump, after the manufacturer factory warranty expires, but will extend coverage to other parts of the vehicle.