Wouldn't the usual opponents being undead already cancel out with the Cleric ending up to spend a lot of his resources on dealing with the worms?
The one thing I'd adjust is turn Undead. Honestly just take it away from Clerics or make it not work on Undead created by worms. It's one of the subfeatures of a subfeatures that does nothing 95% of the time and is pretty broken when it matters. Channel Divinity is pretty good without it for most Clerics, it's not going to hurt them any feelings.
Not to mention that the tired old trope of Paldin/Cleric vs evil is thematic if nothing else. Straight up making the classes less viable or discouraging them is a bit iffy when it makes perfect sense for them to be there.
Lesser Restoration is not exactly uncommon:
Classes: Bard, Cleric, Druid, Paladin, Ranger
Outside of Clerics and Druides, who'd still like to do other stuff with their Spellslots, a second level choice is no joke for a Bard and a rather big expenditure for a half caster.
If you want it to be harder to get rid off don't make it a mundane disease.
Switching the worms to a Curse (Classes: Cleric, Paladin, Warlock, Wizard) will compete with Spirit Guardians/Fireball/Haste and really hurts. Greater Restoration is a massive step up and consumes 100GP worth of diamonds. Your players will scramble for consumables to save their slots for other stuff, even if you let Lesser Restoration work.
It's also possible to scale it as already suggested. The worms coming from a Zombie bite will be weak enough to handle with Lesser Restoration. A stronger Undead like a Wight infecting someone will require Remove Curse first and then Lesser Restoration.