[pikko]

var str="word word 1234567 more words 12345678.12345 and 123456 and 1234567890.1234567 some word";

function splitAllNumbersWithSpacesInString ( str ) {
    str = str.replace(/(\d)(?=(?:\d\d\d)+(?:\D|$))/g, '$1 ');
    return (function delSpaces (str){
        var strNew = str.replace(/(\.\d+)\s(\d+)/g, '$1$2');
        return strNew === str ? strNew : delSpaces(strNew);
    })(str);
}

alert( splitAllNumbersWithSpacesInString(str) );