Here's another example that should work in any SQL as functions used are ANSI SQL standard. This example assumes that there is a whitespace between word 'WEB' and first digit. But it can be improved. I think this is more generic approach then hardcoding start and end positions for subtr:
SELECT TRIM(SUBSTR('WEB 1.0.1', INSTR('WEB 1.0.1', ' ') ) ) as version
FROM dual;
SQL>
VERSION
-------
1.0.1