Hub Bearing Assemblies are the lesser of two evils when tackling your wheel bearings. There are certain advantages of the Hub Bearing Assemblies vs. the Wheel Bearing. It is not a difficult decision when you have a bad bearing. If you have the option of getting a Hub Bearing Assemblies, take it.
The wheel bearing is a precision machined component and it has an important job to do. The 4 wheel bearings in a car hold the weight of the entire vehicle and they have to allow the wheels to roll freely as they do their job. The successful installation of this component is heavily weighted on the proper torque of the axle nut which essentially holds the bearing together. Under torqueing the axle nut lets the bearing separate, over torqueing leads to a grinding sound from the bearing.
For some vehicles your only option is the Wheel Bearing, and this is because the bearing is pressed directly into the knuckle, and the hub is then pressed into the bearing. When installing this type of wheel bearing a hub tamer or press is required; this often makes paying a mechanic to do the job quite worth while if you are not equipped with the proper tools. On the other hand, if you are lucky enough to have a vehicle that has the option to replace the entire hub assembly, a lot less specialized tools are needed. The hub assembly is a housing that has the bearing and hub already pressed into it. Installation consists of removing the defective or worn hub bearing and bolting the new hub bearing assembly to the knuckle.
The other advantage of this design is that the hub bearing assembly often includes the ABS ring and/or speed sensor. These components often suffer damage due to corrosion and dirt contamination. Of course the chances of this happening are reduced when the components are replaced along with the hub assembly.
The general rule is that if your vehicle has the option of replacing the bearing as a complete hub assembly, you are better off replacing the complete hub assembly. You are replacing a variety of components that are always susceptible to damage and wear. The hub bearing assembly is typically easier and less time consuming to install. The extra money you spend on the hub assembly as opposed to just the bearing may even be made up in the labour cost savings.