Replacing the wiper blade inserts on a 2018 Mazda 6, no tools required. The procedure and part numbers are the same for the 2019 Mazda 6. Sure, you could just buy a universal fit wiper blade and replace the whole thing but why not just replace the part that's worn? Plus, the original wiper blade is usually better quality and better looking than the universal ones so it's better to just replace the rubber insert. See the links below for the parts I used:

Driver's Side Insert (GBEF-67-333):
https://www.mazdaswag.com/oem-parts/mazda-wiper-blade-refill-gbef67333
*Wasn't easy to find online, I purchased from local Mazda dealership for around $8

Passenger Side Insert (GBFN-67-333):
https://www.mazdaswag.com/oem-parts/mazda-wiper-blade-refill-gbfn67333
*Wasn't easy to find online, I purchased from local Mazda dealership for around $8