[metroschultz]

As DPoV said, Your tranny uses fluid pressure to shift and thus the only wear you may encounter is on your shifter at its pivots.
However. !Caveat!
Shifting an Auto Trans into gear while rolling at speed over ~ 15MPH is likely to cause internal damage.
Reason.
When you shift into Drive from Neutral, the trans Automatically (it thinks you are stopped) shifts to its lowest gear.
Most trannys shift out of low gear before 15MPH
So
Low gear while rolling at speed will cause an over revving condition which could do damage to you internals.
Think 5spd trans shift to 1st while traveling @ 50MPH
BOOYAH, BANG, OOPS
when I drive my wifes car, an auto, I shift to N when coming to a stop or if I'm cruising through the neighborhood.
When I'm on the highway and using P&G I don't take it out of gear.
I don't have the money to replace her trans right now.
I know my glides are shorter but so is my wallet.
I did knock it out of gear a few times while on the highway and the resulting slam of the harsh engagement told me this was a BAD thing to do. The trans did respond quickly by shifting immediately to OD but it was still enough of a jolt to let me know I was wrong.
I am certain there are trannys out there that will engage the correct gear for the speed. They will be newer units that are completely electronically controlled with far better TCU programming than I have at my disposal.
So that said.
Use your own judgement. (you're intelligent)
Don't let me dictate how you drive. (or anyone else)
Listen to your car. (she knows what she wants)
Drive Safely. (DUH)
Abba goo dai
S.