I think this applies to most atoms in the body over time: https://stevegrand.wordpress.com/2009/01/12/where-do-those-d...

But while it applies to many cells over varied lengths of time (up to many years), it doesn't apply to all cells.

https://www.livescience.com/33179-does-human-body-replace-ce...

https://www.snopes.com/fact-check/does-body-replace-itself-s...

So the idea does apply but not exactly as you claim and it's definitely not absolute, even for atoms, let alone cells.