The standard plastic covers are quite cheap to repair if scratched (about £35 each?). They seem to sustain impact abuse pretty well, but in case of slide on tarmac probably offers very little in term of abrasion resistance.
It’s also a good idea to inspect those protections from time to time for trapped gravel, as those may scratch the tank on a fall.
KTM offers a carbon fiber replacement in the catalog (p/n 63503990044, about £306) which is default equipment in the R Rally.
In the UK Kodama composite is offering a carbon/kevlar cover to put on top of the existing plastic protection, adding the abrasion resistance (Kevlar is very resistant to abrasion, carbon by itself is not). £110. (source)
Rade/Garage makes swanky replacements for the tank protectors in carbon/kevlar. €279.
Fuel tank spigot protection
Even with the side protections, the spigot output of the fuel tank on the left side is a bit exposed, and it’s a plastic knuckle that can break.
KTM Fixed this on the 890 Adventure with a fuel pump cover, P/N 63507087010, €15, which seems to fit the 790.
Also available is a simple plastic guard available to screw on top (€75) to protect it. on impact that part will take the brunt of the impact, protecting the spigot.