Nobody can pinpoint this without looking at the car for you and hearing the noise. Sounds odd to only happen when wet but stranger things than that can happen.

Did you already check the condition of your oil pump?

check your tire size must all be the same size.even the make. makes a difference

You can diagnose your vehicle using a scan tool to know if there is a stored trouble code in your vehicle.

To have an idea on how to replace a power steering pump you can click this link http://www.automd.com/.../ and you will find there a step by step guide, what tools are needed and a video on how to replace a power steering pump (just click the watch video).

sounds like your wheel bearings are worn out

BAD CV JOINT OR HALF SHAFT

YOU SHOULD HAVE STANDARD AIR SHOCKS ,CHECK AIR LINES AND CONNECTORS TO SHOCKS, MAKE SURE THE SHOCK AIR BAG DOES NOT LEAK LOOK FOR DAMAGE TO SHOCK.

If your lower control arm is broken, you have to replace the entire assembly. You cannot just fix one part of it, some people might disagree and say it can be repaired but i wouldn't gamble on the control arm since it supports my vehicle.

The only thing i repair in my control arm are the ball joints and bushings, if its the arm itself, i buy a new one

You likely cannot because you will need the fault codes that are stored related to the fault for the stability control. Access to that info can only be with a full function shop grade level scan tool to access the suspension module.

It might need a new rack and pinion. The vehicle has a system called magnasteer. The system can set fault codes in memory but will require a shop grade scan tool to access them. There may or may not be fault codes but this must be checked before throwing parts at the car. If I were you, I would stop at a Cadillac parts dept with $30 worth of coffee and three dozen donuts, and kindly ask (bribe) nicely if you could chat with a tech for a minute. Trust me, they will know what your car needs if you explain it to them like you did here. They do this every day on the same cars every day. they will know. Since you already replaced the pump, what is left is the rack and the electrical sensors and there is a thing called the Variable Effort Steering Actuator.

It is possible that your steering gear needs to be lubricated or repaired. The other possible causes are

•your power steering belt is damaged or broken

•your power steering reservoir fluid level is low

•your wheels may out of alignment

•your tire pressure is low

maybe your control arms...if so go to ROCKAUTO.COM...GOOD PRICE

It needs struts.

yes struts