The oil pump is around the nose of the crankshaft. The front alloy housing, with the timing chain inside, is also the oil pump housing. A new oil pump, means a complete new housing.
If you do not know where it is, this means you have not removed it for inspection or diagnosis. Oil pumps rarely fail, unless contaminated with swarf or debris, in which case, the oil pump is the least of your worries. Oil pressure sensors have been known to fail, and if fitted with a DPF, the oil can be contaminated with fuel, and with it thinner, pressure is lost.
If you describe your problem, symptoms, and diagnosis carried out so far, others may be able to help.