remove the batteries, esc, receiver, servos... put it aside and let it dry, then remove all bearings and soak it with WD40, then after a day or two, dry the bearings and add bearing oil... and the screws.... no need to change unless you want to have an excuse to change to TRF blue law...
let them (esc, receiver and servo) sit and dry for a few days, take the buggy apart and clean the old grease, add new grease. Then remove the bearings and follow the instructions I just gave you... then put them back together and that's it!
But I think your ESC likely is totalled.. the receiver and servo "might" have a chance to servive... try them after a few days of drying man... good luck...