Yes — the surface cells lining the inside of your stomach replace themselves about every 3 to 5 days, because the acid and enzymes in your stomach would otherwise start digesting the stomach itself.
Digesting food means breaking down protein — and the stomach wall is made of protein too. The acid and enzymes that handle a meal do not know the difference between dinner and the organ holding it. So the stomach defends itself in layers.
The first defense is mucus. The wall stays coated with a thick, protective layer that keeps the harshest contents from sitting directly against the tissue. The second defense is replacement: surface cells are shed and swapped out so quickly that damage does not get time to add up.
This is not your body scrambling after an injury. It is the normal schedule. Cells are born in the glands of the stomach lining, move up to the surface, do their short shift in a brutal environment, and are replaced — over and over, your whole life. When that mucus-and-renewal system breaks down, acid can injure the wall, which is part of how ulcers form.
See the short version in the LOE PRESSURE "Things You Didn't Know" series — Episode 23, the stomach's new lining.
▶ Watch on TikTok→ Do Different Tears Really Look Different Under a Microscope? (coming in a later episode)
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Sources: OpenStax Anatomy & Physiology; Encyclopaedia Britannica, gastric mucosa coverage.