It's probably the heat. I just installed a new water pump; it only lasted 70k. That is shocking because the original one lasted 145k.
Another gen2 iverter pump failure on 2008/9 with the updated pump luckily still under warranty for the OP. These pumps seem no better than the one's they replace.
Inverter coolant quickly gets contaminated with aluminum corrosion as evidenced by white film on cap especially from new. I Coolant see's extensive raw aluminum in heatsinks of Inverter. Aluminum is super corrosive. Take some of your I coolant out an look at it in clear glass and compare to fresh SLLC. Contaminated fluid very abrasive and hard on pump. Changed my I Coolant at 30K and no longer see white dusty film. Plus I installed half a bottle of this: Red Line Synthetic Oil - WaterWetter® Coolant Additives - WaterWetter® I also run a bottle in the ICE coolant. Excellent aluminum anti corrosion additive. Use it in all my cars for years. Greatly extends life of coolant and helps with coolant heat transfer. Rads looks brand new after years of use. Great product.
This is the first time I've seen this suggested as the cause of early pump demise, but it makes sense. Redesigned or not, with bearings running in coolant, this would trash them. BTW, Luscious Garage says the newer pumps are failing, just like the old ones.
Toyota's take seems to be that a winding wire is corroding, leading to pump failure. Not bearing failure, as I'd thought. Time will tell.