There is no real need to escape the quotes :) 
$string = 'a b c la la a b c la la';
$substring = 'b c';
$string =~ s/\Q$substring\E/"$substring"/gi;
print $string;
__END__
a "b c" la la a "b c" la la

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In reply to Re^2: How to substitute a string containing "\" with same string in quotes. by Anonymous Monk
in thread How to substitute a string containing "\" with same string in quotes. by Rapunzel

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