Hey, welcome here.
Without knowing a few more details like pool size and where you live, it's hard to give you any accurate feedback, but if we make a few assumptions, it's fairly easy to guess whether the tech was right or not.
It's unlikely that the bearings in a pump will die from condensation. Although we don't know all the details of the pump that you have, it's safe to say that generally swimming pool pumps are specifically designed to run in humid conditions, and are unlikely to fail from a bit of moisture or condensation. If you poke around long enough here, you will see some photos of some pretty rusty pumps that sit outside all year, and run fine for many years. I'm sure that someone could come up with some pathological case where the conditions would be just right for the pump (really the motor) to fail due to cycling, but that notwithstanding, in virtually any practical installation running the pump less will save you money.
Here is an example based on a typical Hayward 1 HP superpump.
For this example we will assume...
Electrical draw is .75 kW (according to the manual)
Electricity cost of $0.15 / kW hour...
Typical pump replacement cost $343 -- determined by an exhaustive google search grabbing the first price I saw
Typical cost of operation would be.
.......................Hours / Day...........6.............8............12.........24
Cost / Day..................................$0.68.....$0.90.......$1.35.......$2.70
Cost / Month.............................$20.25....$27.00......$40.50......$81.00
3 months..................................$60.75....$81.00.....$121.00....$243.00
6 months.................................$121.50...$162.00....$243.00....$486.00
9 months.................................$182.25...$243.00....$364.00....$729.00
As you can see, if you run 12 hours / day instead of 24, you would save more than the cost of the pump within 9 months. At 8 hours instead of 24, you would save the cost in just over 6 months.
Depending on where you live, those 6-9 months may take two or three calendar years to use. On the other hand, if you live where it is warm, you may save the cost of a pump within the first year.