Is it hard to fix or replace oil pump?

Hello,
The ticking noise typically caused by lifters in the engine, as there is little time before the oil reaches the lifters, it will make the ticking noise then it goes away.
Excessive lifter noise can be caused by a weak oil pump.

The oil pump is located in the timing chain cover. It is driven by the crankshaft.
In order to replace the pump, first you will have to drain the oil and remove the oil pan.

I have attached diagrams for your reference.

Please let me know if you have any questions.
Thank you.