Which sentence sounds better? Why?
- His camera accompanied him everywhere he went in the world.
- His camera accompanied him wherever he went in the world.
Which sentence sounds better? Why?
The first suggests distance, the latter frequency or depth.
If the first were chosen, would think the photographer was wide ranging. The second gives me no sense of his range, but it sounds like he chronicled all he saw around him.
The first sense belongs to a National Geographic field photographer, the second to Diane Arbus or Weegee.
To my ear the first implies many and frequent short journeys to widely diverse region of the globe; while the second implies fewer yet longer journeys to a more selective set of destinations.
I believe the distinction is a straightforward consequence of the definition distinction pointed out above by Kris: everywhere as in or to all places compared to wherever meaning in or to whatever place.
FYI, neither word is in Gardner's "Modern American Usage," so maybe dictionaries offer best advice. Merriam lists "wherever" and syn for everywhere. Of both words, Merriam and Cambridge list "to, in" all places but for "everywhere" they add the concept of "the whole of a place."
So "accompanied him everywhere" seems the stronger statement.
In general English usage, the expressions are synonymous for the OP's context.
eve·ry·where
Adverb
In or to all places.
Noun
All places or directions: "everywhere was in darkness".
Synonyms throughout - anywherewher·ev·er
Adverb
In or to whatever place (emphasizing a lack of restriction): "meet me wherever you like".
meta: Beyond that, any attempt to attribute subtle differences of implications would be, not in the domain of language and its usage, but a matter of interpretation, litcrit and individual opinion. Going there would turn the question off-topic.