Replacing just the power steering pump is possible, but it may not be the best option in some cases. A power steering pump helps to provide pressure and flow of hydraulic fluid throughout the system, which is why it's important to consider all factors when deciding if replacing just this component is sufficient. If other components of the system are worn out or damaged, replacing only the power steering pump won't solve any issues; instead, you'll need to replace multiple parts for a complete repair. Additionally, if your car has an integrated power steering reservoir, then it may not be possible to replace only this part as they often come together as a single unit. Before making any decisions regarding replacement parts and repairs, it's always best to consult with a professional mechanic who can inspect your vehicle and determine what needs fixing and whether you should replace just one component or several.