Baby wipes are better than just water at cleaning a babies or toddlers skin and even adults skin.
The baby wipes often contain soap or cleanser that can help clean the skin better and kill germs.
Baby wipes also remove oily substances on the skin which water cannot and can help maintain the balance of the skins pH.
Water wipes are also good and don't cause irritation to a babies sensitive skin.
If you can't afford wipes for your baby or toddler then using a wet washcloth will work just fine though.
There's been times when I've ran out of baby wipes and simply used a wet washcloth with water and cleaned by kids and babies during diaper changes.
Sometimes I would put some baby body wash in a tub and dip it in the tub and then use that.
Then I would use a second washcloth with just water to wash the soap off.
If the baby just peed there's really no need to use baby wipes or even a washcloth unless the skin has pee on it.
Or if you use cloth diapers then you should wipe after pee but disposable diapers absorb the pee really good.
You could also use the shower to shower your baby or toddler off if they poop and you have no wipes.